This invention relates to dynamoelectric machines and more particularly to electric motors and methods of assembling the stationary members thereof.
Fractional horsepower electric motors commonly include a stator comprised of a plurality of stacked laminations and having a central opening for receiving a rotor. A pair of end frames or end bells are typically provided on opposite ends of the stator structure and serve to rotatably support the rotor.
Proper radial and axial alignment between the motor components must be maintained in order to provide for free rotation of the rotor, to prevent excessive eccentricity in the annular air gap between the rotor and the stator and to prevent excessive axial rotor thrust. Numerous means for securing motor end bells to the stator have been used. These means include through bolts, welding, lances between the frame and each end bell, gluing, etc. Each of these assembly systems does not compensate for varying frame lengths resulting from distortion in the stator stack thickness. Thus motor assemblies tend to vary slightly in overall length because of variations in the thickness of the elements used to construct the stator. Furthermore, these means for securing motor end bells are not readily adaptable to automatic assembly. It is therefore desirable to devise a motor assembly scheme which inherently compensates for varying frame lengths and distortion in stator thickness, while providing positive axial alignment of stator and end bell structures, and which is readily adaptable to automatic motor assembly.